PSMB5 and fragile X-associated tremor/ataxia syndrome: The fragile X–associated tremor/ataxia syndrome (FXTAS) is an adult-onset, progressive neurodegenerative disorder that affects individuals with a premutation (between 55 and 200 CGG repeats) in the fragile X mental retardation 1 (FMR1) gene (Hagerman et al., 2001; Jacquemont et al., 2003).